NROL-55 is scheduled for launch on an Atlas V-401, from VAFB, on 2015 Oct 08, during a launch window that opens at 12:49
UTC. The window probably is planar, which would open about 14 min. earlier each day.
Live coverage will be available here:
http://spaceflightnow.com/2015/10/01/av-059-journal/
The primary payload is the NOSS 3-7 pair of satellites, which will replace the NOSS 3-3 pair launched in 2005. I base
this on a well-established pattern.
NOSS 3-5, launched on 2011 Apr 15, replaced the NOSS 3-1 pair, which ceased to orbit in formation about 7 months later,
shortly after 2011 Nov 07. They had been in orbit just over 10 years. The plane of NOSS 3-5 is about 22 deg west of the
NOSS 3-1 plane.
NOSS 3-6, launched on 2012 Sep 13, replaced the NOSS 3-2 pair, which ceased to orbit in formation about 8 months later,
shortly after 2013 May 21. They had been in orbit about 9.5 years. The plane of NOSS 3-6 is about 15 deg west of the
NOSS 3-2 plane.
NOSS 3-3 was launched in February 2005. Assuming the pair cease to orbit in formation 7-8 months after NOSS 3-7 reaches
orbit, they will have operated for about 11 years. The plane of NOSS 3-7 will be about 30 deg west of the NOSS 3-3
plane.
NROL-79, slated for launch from VAFB in August 2017, is likely to carry NOSS 3-8, which would replace NOSS 3-4, launched
in June 2007.
Here are estimated initial NOSS 3-7 elements, assuming launch at window open:
NOSS 3-7 1013 X 1200 km
1 79701U 15281.61469908 .00000000 00000-0 00000-0 0 07
2 79701 63.4283 292.5778 0124892 180.5274 352.9095 13.40429195 06
Centaur final orbit 459 X 775 km
1 79702U 15281.65902778 .00000000 00000-0 00000-0 0 09
2 79702 64.6863 291.3514 0225821 294.8437 113.6381 14.83391172 04
The above are derived from the NOSS 3-6 launch. Twenty-four hours after launch, allow for at least several minutes time
error, and several degrees of track error on high elevation passes.
In the northern hemisphere, the NOSS orbit will be well-placed for all night observation. Southern hemisphere observers
will have evening visibility, but near twilight.
Here is my recent post on the effects of a significant orbital perturbation that affects the NOSS orbit, and how it is
managed by the NOSS 3 satellites:
http://satobs.org/seesat/Jul-2015/0149.html
More information on the U.S. NOSS and China's copy of an earlier U.S. three-satellite NOSS system is available here:
http://www.satobs.org/noss.html
Happy hunting!
Ted Molczan
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